Human body malodors are generally believed to be caused in part by by-products of microbial interaction with sweat gland secretions. Aside from cleansing, one way to control such odors is by the use of deodorant or antiperspirant products, particularly in the underarm area of the body.
Deodorant and antiperspirant products may be in any of several forms including, for example, creams, liquids, aerosol liquids solid sticks. Many consumers prefer solid stick-type products. Due to the particular types of ingredients employed in deodorants versus antiperspirants, deodorant sticks are typically of the gel-type, whereas antiperspirant sticks are typically of the wax-type.
Gel stick deodorant compositions have several advantages over other types of stick formulations. For example solid gel sticks glide more smoothly over the skin when applied than wax-type sticks. Furthermore gel sticks tend to leave less visible residue on the skin than wax-type sticks.
Solid deodorant gel stick products generally consist of a safe and effective level of an antimicrobial active ingredient which is incorporated into a solid stick base comprising a solidifying agent, a liquid matrix material to carry the active and non-volatile silicone and/or hydrocarbon emollients to deliver the desired cosmetic feel.
The solidifying agents most often used in the solid base component of gel stick deodorants include fatty acid soaps, particularly sodium stearate, and/or dibenzylidine monosorbitol acetals (hereinafter DBS). The following exemplary patents relate to gel stick compositions utilizing soap solidifying agents: U.S. Pat. Nos. 3,255,082, Barton, issued Jun. 7, 1966; 4,137,306, Rubino, issued Jan. 30, 1979; 4,944,937, McCall, issued Jul. 31, 1990. The following exemplary patents relate to gel stick compositions utilizing DBS solidifying agents: U.S. Pat. Nos. 4,154,816, Roehl et al, issued May 15, 1979; 4,518,582, Schamper et al, issued May 21, 1985; 4,719,102, Randhawa et al, issued Jan. 12, 1988; 4,722,835, Schamper et al, issued Feb. 2, 1988; 4,725,430, Schamper et al, issued Feb. 16, 1988; 4,781,917, Luebbe et al, issued Nov. 1, 1988; 4,816,261, Luebbe et al, issued Mar. 28, 1989; 4,822,602, Sabetelli, issued Apr. 18, 1989; and 5,106,999, Gardlik et al, issued Apr. 21, 1992.
The liquid matrix materials of the solid base component of soap-type and DBS-based gel stick deodorants typically include lower molecular weight alcohols (such as ethanol and isopropanol), and glycols (such as propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol and various higher polyethylene and polypropylene glycols). The following exemplary patent relates gel stick compositions utilizing alcohols and glycols: U.S. Pat. No. 4,137,306, Rubino, issued Jan. 30, 1979. Low molecular weight alcohols and glycols, however, tend to contribute to undesirable performance characteristics such as skin irritation and undesirable stick shrinkage and containment problems due to high volatility.
Silicone and hydrocarbon emollients are used in typical cosmetic stick deodorants. One type of preferred non-volatile silicone emollient for deodorant sticks is dimethicone. Hydrocarbon emollients typically used in gel stick deodorants include fatty acid and fatty alcohol esters and water insoluble ethers, such as those disclosed in U.S. Pat. No. 4,202,876, Shelton, issued May 13, 1980.
Deodorant compositions typically contain an antimicrobial active ingredient at levels of from about 0.1% to about 10% by weight. Examples of such antimicrobial active ingredients typically included in deodorant compositions include the primary oleamine salt of piroctone (known commercially as Octopirox.RTM.), certain metal salts of piroctone acid (such as aluminum, sodium, potassium, zirconium, calcium and zinc metal salts), triclosan, zinc phenolsulfonate, certain heavy metal salts of 1-hydroxy pyridinethione (such as zinc pyrithione, magnesium pyrithione, and aluminum pyrithione) and bacteriostatic quaternary ammonium compounds (such as cetyl-trimethyl ammonium bromide, cetyl pyridinium chloride, benzethonium chloride, and sodium N-lauryl-sarcosine).
Certain astringent metal salts, particularly aluminum and zirconium astringent salts and complexes and some zinc salts, typically used in antiperspirant compositions at levels above about 10% by weight have also been shown to provide deodorancy benefits when employed at levels below about 10% without the antiperspirancy effects. See Plechner, Antiperspirants and Deodorants, Cosmetics, Science and Technology--Volume 2, Balsam and Sagarin, 374-411, 1972.
Although shown to provide excellent deodorancy characteristics, astringent metal salts have not generally been used in deodorant solid gel stick products primarily due to incompatibility between the soap-type gellants and poly-valent salts (cations bearing greater than +1 charge). Without being limited by theory, it is believed that the metal salt active interacts with the carboxylate functional group on the fatty acid soap resulting in reduced deodorancy efficacy and loss of integrity of the solid itself, resulting in significant softening of the solid stick product.
The aluminum salt actives are also incompatible with DBS and DBS-type solidifying agents, as they tends to degrade the acetal portion of the DBS gellant resulting in reduced efficacy of the actives, poor gel formation, and lower gel stability over time, as well as processing difficulties at the temperatures and holding times typically encountered during manufacturing of the deodorant compositions.
It would be desirable, in view of the excellent deodorancy characteristics of metal salt actives, to incorporate them into cosmetic stick deodorant compositions which provide a stable product with the wet, smooth cosmetic feel and low visible residue typical of deodorant gel sticks. It would also be desirable, in view of the skin-irritation characteristics of low-molecular weight alcohols and glycols to omit or strictly limit the amount of these materials contained in the composition.
The present inventors have found that such cosmetic stick deodorant compositions with astringent metal salt actives, can be produced by incorporating wax solidifying agents in combination with high levels of volatile and non-volatile emollients. The inventors have also found that the efficacy of the astringent metal salt actives can be even further improved by the addition of a surfactant with a high hydrophile-lipophile balance value.
It is therefore an objective of the present invention to provide a deodorant cosmetic stick composition, in which astringent metal salts are used as the deodorant active in a stable, anhydrous base component which exhibits a wet, smooth cosmetic feel and low visible residue. It is a further object of this invention to provide deodorant cosmetic stick compositions which are not irritating to the skin due to low molecular weight alcohols and glycols.